1. Field of the Invention
The present invention relates to an active matrix type liquid crystal display in which liquid crystal is driven by an electric field of components in parallel with the surface of a panel substrate.
2. Description of the Related Art
For liquid crystal displays, as one system to apply an electric field to liquid crystal, there is a static drive system to stationarily supply a constant voltage signal to each electrode. However, when a display of large capacity is performed, a very large number of pieces of signal lines are required in a static drive system. Therefore, recently, when a display of large capacity is performed, generally, a multiplex drive system to supply signal voltage by time sharing is employed.
Among multiplex drive systems, according to an active matrix system in which the electric charge applied to an electrode is held until the next frame is displayed, a display of a high grade is performed.
Furthermore, among active matrix systems, there are a system in which an electric field of components perpendicular to the surface of a panel substrate is applied to liquid crystal, and a system in which an electric field of components parallel to the surface of a panel substrate is applied to liquid crystal (In-Plane Switching system, hereafter, referred to simply as xe2x80x9cIPS systemxe2x80x9d), with respect to the direction of an electric field applied to liquid crystal. Among them, the IPS system is suitable for the use of a large monitor since a wide angle of visibility can be obtained.
For example, a liquid crystal display of the latter IPS system is proposed in Japanese Patent Laid-Open Publication No. 7-225388 (published on Aug. 22, 1995). In the conventional liquid crystal display, retardation of the liquid crystal composition layer is 0.21 to 0.36 xcexcm. The retardation of the liquid crystal composition layer means the product (xcex94nxc2x7d) of the refractive index anisotropy xcex94n and the thickness of the liquid crystal layer (cell gap) d.
However, in a conventional liquid crystal display of the IPS system, there is such a problem that a phenomenon of blue staining or yellow staining occurs because of the refractive index anisotropy of a liquid crystal molecule when a screen is viewed from a severely slant view at a comparatively large visual angle. Such a phenomenon is called color-tint. Especially, the grade of yellow staining is remarkable, and it is difficult for the original color viewed from the front to reappear.
It is an object of the present invention to provide an active matrix type liquid crystal display of the IPS system in which a good color reproducibility is obtained regardless of the angle of visibility.
According to one aspect of the present invention, an active matrix type liquid crystal display may has a liquid crystal display panel. The liquid crystal display panel may comprise two substrates and a liquid crystal layer provided between the two substrates. The product xe2x80x9cxcex94nxc2x7dxe2x80x9d of the refractive index anisotropy xcex94n of a liquid crystal material in the liquid crystal layer and the thickness d of the liquid crystal layer is preferably 0.12 to 0.18 xcexcm.
According to one aspect of the present invention, at all angles of visibility, the shift of chromaticity, especially the shift to yellow can be restrained. Furthermore, according to one aspect of the present invention, in some cases, the liquid crystal display panel may be stained blue when displaying halftone of white, but the effect to restrain the shift to yellow with a high luminosity is larger since the luminosity of blue is extremely lower than that of yellow. As a result, a good color reproducibility can be obtained regardless of the angle of visibility.